<template>
  <div class="spec-preview">
    <!--默认的底图-->
    <img :src="imgUrl ? imgUrl : skuInfo.skuDefaultImg" />
    <div class="event"  @mousemove="move" ref="event"></div>
    <!--大图区域-->
    <div class="big">
      <img :src="imgUrl ? imgUrl : skuInfo.skuDefaultImg" ref="bigImage" />
    </div>
    <!--滑块区域-->
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
  import {mapGetters} from "vuex"
  export default {
    name: "Zoom",
    data(){
      return {
        index:"", //当前选中的图片下标
        imgUrl:""
      }
    },
    computed:{
      ...mapGetters(["skuInfo"])
    },
    methods:{
      move(ev){
        //实现整个放大镜效果  mousemove事件一定要加给event元素!
        let maskNode = this.$refs.mask;
        let eventNode = this.$refs.event;
        let bigImageNode = this.$refs.bigImage;
        //鼠标在实时滑动时 距离滑屏区域的距离(x,y)
        let x = ev.offsetX;
        let y = ev.offsetY;
        //滑块移动的实时距离(left top)
        let left = x-(maskNode.offsetWidth/2);
        let top = y-(maskNode.offsetHeight/2);
        //边界处理
        if(left<0){left=0}
        if(top<0){top=0}
        if(left > eventNode.clientWidth-maskNode.offsetWidth){
          left=eventNode.clientWidth-maskNode.offsetWidth
        }
        if(top > eventNode.clientHeight-maskNode.offsetHeight){
          top=eventNode.clientHeight-maskNode.offsetHeight
        }
        //滑块移动
        maskNode.style.left = `${left}px`
        maskNode.style.top = `${top}px`
        //大图的移动
        bigImageNode.style.left = `${-2*left}px`
        bigImageNode.style.top = `${-2*top}px`
      }
    },
    mounted() {
      this.$bus.$on("picChange",(pic)=>{
        this.imgUrl = pic.imgUrl
      })
    }
  }
</script>

<style lang="less">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }

    .event:hover~.mask,
    .event:hover~.big {
      display: block;
    }
  }
</style>